AC troubleshooting

[Dantheman1540]

So my AC suddenly became moist and ambient. Upon investigation the low pressure port was leaking a little. Hooked up my gauges and this is what its showing. Quick Google search of what pressure is good shows 30-45psi for low side and ambient plus 100 for high side so about 180-190psi. If that's true then is my system over pressured?

Also I was able to stop the low pressure port leaking.

 

[2010gmcyukon]

How were you able to stop the low pressure port leaking? I believe mine is too.

 

[Dantheman1540]

How were you able to stop the low pressure port leaking? I believe mine is too.

I simply reset the valve stem by attaching and removing the pressure gauge. Might take a couple tries. If you don't have a fitting that will connect you can use a small screw driver or something to depress the valve stem which may reset it.

After a little more AC reading I think Mine may be low which is why the compressor kicks on and off. Going to fill it up tonight and see what it do.

 

[PG01]

lets ask brent what he thinks... @BG1988
brent, any ideas?

 

[79jasper]

Quick Google search of what pressure is good shows 30-45psi for low side and ambient plus 100 for high side so about 180-190psi. If that's true then is my system over pressured?

Should be closer to (ambient x2) + 50.
You leak was likely self inflicted.(been there) Don't screw the valve all the way in. Just enough to move the gauge.
Also, it's actually normal for the ac compressor to cycle a bit.
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[OR VietVet]

It does look like the readings show low and that is backed up by the leaking shrader valve, They do make a special tool to tighten the valve as well. It looks just like the same type of tool used to remove and replace a tire vale stem, only bigger. The vales do get sticky with age. I would add a pound of R134A and see where the gauges go. Yes, it is normal for a/c systems to cycle.

 

[PG01]

c’mon, nobody want brent to chime in?

 

[M123]

Some ac systems on cars can break the circuit to the high pressure valve if the fan on the
radiator are working bad or not at all.
Now I don't know what type of fan you have.

Doesn't the OBD 2 read the AC or ACC on Tahoe's?

 

[79jasper]

They do make a special tool to tighten the valve as well. It looks just like the same type of tool used to remove and replace a tire vale stem, only bigger.

Just to clarify, I meant the valve on the quick disconnect for the manifold gauge.
I don't know what year started monitoring the pressure through the pcm.

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[Dantheman1540]

Well I found the leaky valve stem before I ever touched the system. Was driving and the AC went warm and moist. Made it home and popped the hood to find a gurgling low side port with a little dye and some bubbles around it. Tahoe never had the port caps on it when I bought it and I never put any on so I really don't know how the valve stem would suddenly start leaking while driving. However after resetting it with the Gauges QD it stopped leaking.

Gonna swing by Harbor freight on the way home and grab a few cans of that covid coolant.